This section is intended to introduce the reader to various aspects of art, which may be related to various aspects of the present invention that are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
The so-called ‘second screen’ is becoming more and more widespread. It may be said to be an auxiliary electronic device such as a tablet or a smartphone that interacts with, usually, a television (‘main screen’) in order to provide interactivity with or additional information to the content displayed on the main screen. An example is showing a baseball game on the main screen and player statistics on the second screen. Another example is an interactive quiz show where answers to questions presented on the main screen may be entered using the second screen so that the spectator may participate in the game.
It will be appreciated that there is a need for synchronization between the content displayed on the main screen and the content displayed on the second screen, in particular when it comes to live content.
So far, three main techniques have been used to provide the synchronization: metadata, fingerprinting and watermarking.
In the metadata technique, the broadcaster embeds metadata in the video data stream. At the user's premises, the video data stream is separated from the metadata by e.g. the main screen itself or a Set-Top Box (STB). The main screen thus receives and renders the video data stream, while the metadata is sent to the second screen, which uses part of the metadata for synchronization of the rest of the metadata with the video data stream. A drawback of this technique is the need for a connection between the device that separates and sends the metadata and the second screen.
In the fingerprinting technique, the video data stream is sent to the main screen where it is rendered. The second screen captures at least part of the rendered content, preferably the audio, and computes audio fingerprints, so-called “DNA” fingerprints. The second screen then sends the DNA fingerprints to a special server that computes (or receives from the broadcasters) DNA fingerprints for a plurality of channels and compares the DNA fingerprint received from the second screen with its own DNA fingerprints. When there is a match, the server returns the channel and the time to the second screen. Drawbacks with this solution is that the architecture is rather complex and costly (it is time and resource consuming). In addition, the server cannot tell the difference between two channels that broadcast the same content.
In the watermarking technique, the broadcaster inserts a watermark in the audio part of the video data stream. The watermark uniquely identifies the time and the channel. When the main screen renders the content, the second screen is able to capture the audio, extract the watermark and obtain the time and the channel. A drawback is that the broadcaster has to watermark the content, which is not always desired since it requires a modification to the content workflow and since the watermark may have a cost (performance, license, audio quality, etc.).
It will thus be appreciated that there is a need for a solution provides an improved technique for synchronization between a main screen and a second screen. The present invention provides such a solution.